High Capacity Color Barcodes: Per Channel Data Encoding via Orientation Modulation in Elliptical Dot Arrays

Abstract

Abstract-We present a new high capacity color barcode. The barcode we propose uses the cyan, magenta, and yellow (C,M,Y) colorant separations available in color printers and enables high capacity by independently encoding data in each of these separations. In each colorant channel, payload data is conveyed by using a periodic array of elliptically shaped dots whose individual orientations are modulated to encode the data. The orientation based data encoding provides beneficial robustness against printer and scanner tone variations. The overall color barcode is obtained when these color separations are printed in overlay as is common in color printing. A reader recovers the barcode data from a conventional color scan of the barcode, using red, green, and blue (R,G,B) channels complementary, respectively, to the print C, M, and Y channels. For each channel, first the periodic arrangement of dots is exploited at the reader to enable synchronization by compensating for both global rotation/scaling in scanning and local distortion in printing. To overcome the color interference resulting from colorant absorptions in noncomplementary scanner channels, we propose a novel interference minimizing data encoding approach and a statistical channel model (at the reader) that captures the characteristics of the interference, enabling more accurate data recovery. We also employ an error correction methodology that effectively utilizes the channel model. The experimental results show that the proposed method works well, offering (error-free) operational rates that are comparable to or better than the highest capacity barcodes known in the literature.Index Terms-Color barcodes, color interference aware encoding, elliptical dot barcodes, high capacity barcodes, sequential decoding.

Orientation Modulation for Data Hiding in Chrominance Channels of Direct Binary Search Halftone Prints

“…This approach achieves high robustness to the print-and-scan channel, and it also offers high data hiding capacity. This technique was extended to color barcodes, 16 but not to images with arbitrary content.…”

Improved color barcodes via Expectation Maximization style interference cancellation

“…Because barcodes consume precious spatial "real-estate" on physical media, high capacity barcodes that increase the information density per unit area are highly desirable. Recently the latitude offered by color reproduction has been actively studied to increase the capacity of monochrome barcodes [3][4][5][6][7][8][9].…”

“…The method is particularly attractive because most image capture devices already provide RGB color capture and because the monochrome barcode techniques are quite mature in their development. The method proposed in [9] offers an example of a barcode using this methodology, which we will use as a specific focused example for our presentation, even though the method we propose here can be more broadly applied.…”

“…For the method in [9], the data in each colorant channel is encoded in elliptical-dot arrays where the orientation of individual elliptical dots is modulated for the purpose of encoding data. The data encoded CMY colorant layers are printed in overlay to generate the color barcode.…”

“…As noted previously, the inter-channel color interference poses a challenge in this setting. In [9] this is circumvented by restricting to binary modulation with a carefully designed signaling constellation that mitigates the interference and by using a sequential error correction decoding that comprehends the interference at the decoder.…”